Description
Return a luminosity ratio from two fluxes and distances.
Cosmology uses several distance measures and often expresses the expansion rate in mixed astronomical units. Scale-factor relations, inverse-Hubble scales and relativistic velocity composition answer different questions; units and the distinction between local algebra and an integrated expansion history are essential.
Return a luminosity ratio from two fluxes and distances.
When to use this tool
Use Flux Luminosity Reference Ratio when checking one explicit cosmological distance, redshift-factor or unit convention.
How to use the tool and how it works
- Enter firstFlux, secondFlux, firstDistance, secondDistance. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read luminosityRatio. Use the output convention below.
Return a luminosity ratio from two fluxes and distances. Require firstFlux >= 0, secondFlux > 0 and positive distances; ratio = (firstFlux/secondFlux)*(firstDistance/secondDistance)².1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| firstFlux | First Flux | Required. Finite number; minimum 0. |
| secondFlux | Second Flux | Required. Finite number; strictly above 0. |
| firstDistance | First Distance | Required. Finite number; strictly above 0. |
| secondDistance | Second Distance | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| luminosityRatio | Luminosity Ratio | Required. Finite number. |
{
"input": {
"firstFlux": 2,
"secondFlux": 1,
"firstDistance": 3,
"secondDistance": 2
},
"output": {
"luminosityRatio": 4.5
}
}Limitations and assumptions
- Use compatible fluxes and luminosity distances; bandpass, attenuation, beaming and spectral corrections are not applied.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use a complete cosmological distance/time calculation and the appropriate observation model when an actual source distance, age or velocity is required.
References
Similar or alternative tools
- Luminosity Angular Distance Duality Residual
Return a distance-duality residual.
- Distance Modulus Hubble Rescale Term
Rescale a distance modulus under inverse-Hubble distance scaling.